fix(certify): reweight when code is unscorable instead of auto-failing

Previously, repos with no Python LOC got code_score=0, causing
automatic FAILED certification even for well-governed Go/Rust/TS
repos. Now reweights to governance 60% + deps 40% when code scoring
is unavailable, with a transparent note in reasons.

Before: prometheus/prometheus → FAILED (47.0)
After:  prometheus/prometheus → CERTIFIED (94.0)

Found by scanning 10 Go repos: all failed despite excellent
governance because code scoring was Python-only.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Claude (agent)

src/arbiter/certify.py

@@ -10,7 +10,6 @@
 from __future__ import annotations
 
 from dataclasses import dataclass, field
-from pathlib import Path
 
 from arbiter.analyzers.base import Finding
 from arbiter.scoring import RepoScore
@@ -68,35 +67,51 @@ def certify(
     """Run full certification assessment.
 
     Weights: code quality 50%, governance 30%, dependencies 20%.
+    When code is unscorable (no Python LOC, analyzers not installed),
+    reweight to governance 60% + dependencies 40% instead of penalizing.
     """
-    code = code_score.overall if code_score.is_scorable else 0
+    code = code_score.overall if code_score.is_scorable else None
     gov = governance_report.score
     deps = dep_report.score
 
-    overall = code * 0.50 + gov * 0.30 + deps * 0.20
+    if code is not None:
+        overall = code * 0.50 + gov * 0.30 + deps * 0.20
+    else:
+        # Reweight: skip code dimension entirely
+        overall = gov * 0.60 + deps * 0.40
+        code = 0  # for display purposes
+
     overall = round(overall, 1)
 
     reasons = []
+    code_scorable = code_score.is_scorable
 
     # Determine decision
     cert = CERT_THRESHOLDS["certified"]
     prov = CERT_THRESHOLDS["provisional"]
 
-    if (overall >= cert["overall"] and code >= cert["code"]
+    # Skip code threshold checks when code is unscorable
+    code_meets_cert = code >= cert["code"] if code_scorable else True
+    code_meets_prov = code >= prov["code"] if code_scorable else True
+
+    if not code_scorable:
+        reasons.append("Code quality not scored (no supported analyzers for primary language)")
+
+    if (overall >= cert["overall"] and code_meets_cert
             and gov >= cert["governance"] and deps >= cert["deps"]):
         decision = "CERTIFIED"
-    elif (overall >= prov["overall"] and code >= prov["code"]
+    elif (overall >= prov["overall"] and code_meets_prov
             and gov >= prov["governance"] and deps >= prov["deps"]):
         decision = "PROVISIONAL"
-        if code < cert["code"]:
+        if code_scorable and code < cert["code"]:
             reasons.append(f"Code score {code:.1f} below certified threshold ({cert['code']})")
         if gov < cert["governance"]:
             reasons.append(f"Governance score {gov:.1f} below certified threshold ({cert['governance']})")
         if deps < cert["deps"]:
             reasons.append(f"Dependency score {deps:.1f} below certified threshold ({cert['deps']})")
     else:
         decision = "FAILED"
-        if code < prov["code"]:
+        if code_scorable and code < prov["code"]:
             reasons.append(f"Code score {code:.1f} below minimum threshold ({prov['code']})")
         if gov < prov["governance"]:
             reasons.append(f"Governance score {gov:.1f} below minimum threshold ({prov['governance']})")

tests/test_certify.py

@@ -61,9 +61,17 @@ def test_governance_checks_counted(self):
         assert result.governance_checks_passed == 7
         assert result.governance_checks_total == 10
 
-    def test_non_scorable_code(self):
+    def test_non_scorable_code_reweights(self):
+        """Non-scorable code should reweight to governance 60% + deps 40%, not fail."""
         unscorable = RepoScore(overall=0, lint_score=0, security_score=0,
                                complexity_score=0, total_findings=0, is_scorable=False)
         result = certify(unscorable, _FakeGovReport(80), _FakeDepReport(85), [])
-        assert result.code_score == 0
-        assert result.decision == "FAILED"
+        # Reweighted: 80*0.6 + 85*0.4 = 48+34 = 82
+        assert result.overall >= 80
+        assert result.decision == "CERTIFIED"  # governance + deps are strong enough
+
+    def test_non_scorable_notes_reason(self):
+        unscorable = RepoScore(overall=0, lint_score=0, security_score=0,
+                               complexity_score=0, total_findings=0, is_scorable=False)
+        result = certify(unscorable, _FakeGovReport(80), _FakeDepReport(85), [])
+        assert any("not scored" in r for r in result.reasons)